Physicochemical properties, antioxidant and antidiabetic activities of different hydrolysates of goat milk protein

There is growing interest in the origin, preparation, and application of bioactive peptides. This study investigated the effect of 6 enzymes on the structural, physicochemical properties, antioxidant activities, and antidiabetic potential of defatted fresh goat milk. Structural and functional changes resulting from enzymatic hydrolysis were assessed using gel electrophoresis, laser particle size analysis, multi-spectroscopy, and evaluations of foaming and emulsification properties. Antioxidant capacity was determined through free radical scavenging, Fe²⁺ chelation, and reducing ability experiments. Additionally, the inhibitory effects of the hydrolysates on α-glucosidase and α-amylase were measured to evaluate antidiabetic activity. Results showed that enzymatic hydrolysis disrupted the spatial structure of goat milk protein and reduced its molecular weight. Papain hydrolysate exhibited the highest degree of hydrolysis (32.87% ± 0.11%) and smallest particle size (294.75 ± 3.33 nm), followed by alcalase hydrolysate (29.12% ± 0.09%, 302.03 ± 7.28 nm). Alcalase hydrolysate showed the best foaming properties, and papain hydrolysate demonstrated the strongest 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radical scavenging activity, Fe²⁺ chelation, and antidiabetic potential. These findings provide a solid theoretical basis for utilizing defatted goat milk as functional ingredients or excipients in the food, medical, and cosmetic industries.